This sounds like a great idea in theory, but the execution seems to be a little scratchy.

It sounds as though this is very much a unilateral decision from one of the many sites that use Markdown to standardise it, masked by what seems to be a call for other companies with an interest in Markdown to join.

It seems a little questionable to me for John Gruber to have been ignored in this process. Afterall, he made Markdown and it probably would have been a better idea to take his rather ambiguous spec, develop it into a proper standard, and then call that version 1.0.

No doubt Jeff Atwood deserves some credit for trying to initiate a standards process for Markdown, but I think he's doing it the wrong way.